WHAT'S UP DOC? Biliary atresia

Q: My neighbor’s baby developed jaundice and they say it was because the ducts in her liver did not form properly. What is this from?

A: Bile is a digestive fluid made by the liver cells. It flows through tubes (bile ducts) to the gallbladder (to be temporarily stored), and is excreted into the intestines (from the gallbladder as well as directly, as needed). This flow of bile performs several functions. It helps carry toxins and waste that is cleared from the blood by the liver, and once in the intestines it aids in the digestion of fats and in the absorption of fat soluble vitamins (vitamins A, D, E and K).

Biliary atresia (BA) is a rare condition, affecting about 1 in every 10,000 to 20,000 babies, both boys and girls. In patients with BA, the bile tube system, and the openings in these tubes, do not form normally. In these patients the bile that is formed by the liver cells cannot flow normally and hence it builds up, causing damage to the liver. In addition, the bile system cannot perform its normal function, so toxins and waste products also build up in the liver, fats in the intestines are not normally digested, and fat soluble vitamins are not absorbed.

There are three major forms of BA. About three quarters have their BA only affect their bile ducts. About 15 percent have the bile ducts affected as well as a “laterality” abnormality, such as situs inversus (major organs, possibly the heart, liver, spleen and/or other organs, are on the opposite side of the body as they normally are), lack of formation of the spleen, intestinal problems, heart issues and/or abnormalities of the large veins carrying blood returning to the heart. The remaining 10 percent of patients have congenital abnormalities in addition to their bile duct issues, possibly involving the kidneys, heart, intestines and/or other organs.

The exact cause of BA is not known, but it is not an inherited condition. Theories of the causes of BA include in utero infection (possibly viral or bacterial), immune system dysfunction or exposure to toxins.

Symptoms in babies with BA typically manifest several weeks after birth. Bile retention results in jaundice (yellowing of the skin and the whites of the eyes), the most common symptom. Other symptoms from deficient vitamin and/or fat absorption may occur. Severe liver failure can lead to death.

BA is suspected based on the symptoms (especially jaundice starting several weeks after birth, as opposed to the fairly common jaundice that develops within days of birth usually due to more benign reasons), and is confirmed by blood tests (which show the liver abnormalities), imaging tests (including ultrasound, specialized nuclear medicine scan called hepatobiliary scintigraphy, and possible other tests), biopsy (that shows buildup of bile, etc.) and/or cholangiogram (where a dye is injected into the biliary system and x-rays taken to image it, this is typically done as part of a surgical procedure). Visualize of the abnormal ducts during surgery is occasionally needed to definitively confirm the diagnosis.

BA is treated by surgery (the Kasai procedure) to remove the defective bile ducts and to replace them by directly connecting to a piece of small intestine. Because this is not the normal flow pattern of bile, this treatment may not allow the patient to regain completely normal liver function, hence these babies typically need vitamin and triglyceride (the main constituents of natural fats and oils) supplementation in their diets, as well as extra calories (the condition increases the patient’s energy requirements).

The Kasai surgery may not completely prevent abnormal bile (and toxin and waste) buildup in the liver. Hence many of these patients still develop liver failure, eventually requiring a liver transplant (half of patients need a transplant before age 5). In some cases, particularly when there is already significant liver compromise, liver transplant may be needed even earlier in life.

Complications of the Kasai procedure may include infection, leakage of fluid from the liver into the abdomen (ascites), increased blood pressure in the liver (portal hypertension), and/or others. Liver transplant patients need immune system suppression to prevent organ rejection; they may develop complications from this including infection and/or other possible issues.

Although treatment usually starts with the Kasai procedure, over three quarters of patients eventually require a liver transplant. With this care over 90 percent of babies born with BA survive into adulthood.